1. Field of the Invention
The present invention generally relates to an information storage device and a defect information management method. Specifically, the present invention relates to an information storage device and a defect information management method for managing defect information arising when formatting a storage medium.
In recent years and continuing, an information storage device such as a hard disk drive is becoming higher density as it becomes smaller and achieves a greater capacity. In order to store high-density information in a storage medium, format processing is necessary for dividing the tracks of the storage medium into parts of a predetermined number of bytes, which takes much time. Therefore, it is required to perform format processing effectively.
2. Description of the Related Art
FIG. 1 is a block diagram showing a conventional magnetic disk device. The conventional magnetic disk device 1 mainly includes a magnetic disk 2, a spindle motor 3, a magnetic head 4, a head arm 5, a VCM (voice coil motor) 6, rotation axes 7, 8, a driver 9, a micro control unit (MCU) 10, a flash ROM 11, a hard disk controller (HDC) 12, an interface circuit (I/F) 13, a buffer (DRAM) 14 and a read/write channel 15.
The magnetic disk 2 is held by the rotation axis 8 of the spindle motor 3 and is rotated in the direction of the arrow A by the spindle motor 3. The spindle motor 3 is connected to the MCU 10 via the driver 9 and is controlled by the MCU 10 such that the spindle motor 3 rotates at a constant speed. The magnetic head 4 is placed opposite to the magnetic disk 2.
The magnetic head 4 is electrically connected to the read/write channel 15. The read/write channel 15 provides a recording signal to the magnetic head 4 such that information is recorded by magnetizing the magnetic disk 2. The magnetic head 4 is mechanically connected to an end of the head arm 5.
Another end of the head arm 5 is connected to the VCM 6 via the rotation axis 7. The VCM 6 is controlled by the MCU 10 via the driver 9 such that the VCM 6 moves the head arm 5 in the radial direction of the magnetic disk 2, that is, in the direction of the arrow B. As a result, the magnetic head moves in the radial direction of the magnetic disk 2 such that it follows a desired track on the magnetic disk 2.
The driver 9 controls the spindle motor 3 and the VCM 6. The MCU 10 performs format processing for dividing each track of the disk into recording areas of a predetermined byte length. The flash ROM 11 stores processing information for the MCU 10.
The HDC 12 controls the magnetic disk 2 based on information from the interface. The interface circuit 13 is connected to the HDC 12 which captures information from the interface 13. The buffer 14 temporarily stores information such as processing results.
The magnetic disk 2 is formatted according to a predetermined format for writing/reading information. The format processing for the magnetic disk 2 will be described below.
FIG. 2 shows a format of the magnetic disk according to a conventional technique. As preprocessing, a plurality of servo information 16 is configured on the magnetic disk 2 radially from the rotation axis 8 of the spindle motor 3. The servo information 16 includes information by which the magnetic head 4 follows the track 18 of the magnetic disk properly. The track 18 is configured concentrically around the rotation axis 8 of the spindle motor 3 and stores data. Data is stored in a sector which is a data area of a predetermined byte length along the track 18.
Next, processing is performed for detecting a defect part in the recording area 17 between consecutive sets of the servo information 16. The processing will be described.
FIG. 3 is a flowchart showing format processing and pre-processing according to a conventional technique. When performing this processing, the MCU 10 reads out a format processing procedure stored in the flash ROM 11.
In step S1, servo information 16 is written onto the magnetic disk 2. Next, in step S2, defect information is detected while following the track 18 according to servo information 16 for detecting a reading error between consecutive sets of servo information in the recording area. When a reading error is detected between consecutive sets of servo information, defect information which indicates the position of the error is temporarily stored in the buffer memory 14. The stored defect information is converted after format processing and stored in the flash ROM 11. When no error is detected, the processing is continued. After that, in step S3, so-called sectors are generated by dividing the recording area 17 into a plurality of predetermined intervals. In this processing, slip processing is performed when an error is detected between the consecutive sets of servo information, that is, in the sector. In the slip processing, information of the sector with the error is assigned to another sector.
In the format processing in step S3, when an error is detected in servo information, format processing in step 3 is aborted in the conventional technique. In the following, a track format in the above-mentioned formatting operation will be described with a figure.
FIG. 4 shows the track format at the time when defect information is detected according to a conventional example. FIG. 4 shows a servo error 20, format processing direction 30, normal servo information 40 and sectors 50. The recording area 17 is divided at regular intervals sequentially in the format processing direction 30 and addresses are provided. For example, the position of a track is determined from the servo information 40 such that the track is properly followed. After that, the recording area 17 is divided into sectors of a predetermined byte length. Addresses are provided to the sectors sequentially in the processing direction from the index which is a starting point of the track. For example, an address “100” is provided to a sector next to the servo information 40. Then, the sector is called sector 100. In the same way, addresses are provided to the sectors.
When the servo error 20 is detected while format processing, the sector 104 in which the servo error 20 exists becomes the address of the servo error. When a servo error is detected, a next sector can not be followed properly. Therefore, the format processing is aborted due to the servo error. As a result, the drive becomes inaccessible and the format processing needs to start from the beginning.
In the above-mentioned format processing, when a servo error is detected, the track can not be properly followed. Therefore, the format processing is aborted and the drive can not be accessed. Thus, the storage medium in which the servo error is detected can not be used and it is necessary to perform format processing from the beginning or to abandon the storage medium. Accordingly, the format processing can not be continued due to the servo error, which results in ineffectiveness of the format processing.